Urgent contingency plans have been put in place at the Passport Office to cope with the huge demand in passport applications.

It has recruited extra staff to operate telephone helplines with extended opening hours from 07:00 to 22:00 weekdays and from 08:00 to 18:00 at weekends. Back office staff have been redeployed to help clear the reported backlog.

Travellers facing an anxious wait for their passports and are due to travel in the next few days are advised to contact the Passport Office directly on 0300 222 00 00. Anyone who applied for a passport by post or the Check & Send service may be able to upgrade to a Premium service.

The premium service costs £128 and means passports can be collected within four hours of being approved. The fast-track service costs £103 with the passport returned within a week of the application being approved.

Passport chief executive Paul Pugh denied a backlog, claiming that 97% of passport renewals and child passports are being processed within the three week turnaround.

“Staff were brought in immediately to respond to the extra demand; we are operating seven days a week and our couriers are delivering passports within 24 hours of being produced.

“We have issued almost three million passports for UK customers in 2014, including over one million issued in the eight weeks since the start of April,” he said.

Mike Jones, of the PCS union, told the BBC: “Thousands of people complain that it has taken more than two months for them to get passports. That clearly is a backlog.”